ifconfig, vlan support

hi,
I cannot seem to find which program/script sources the
/etc/network/network.conf file.
Does the dhclient program read it, or is there a startup script which
reads it?
also, i compiled the 2.4.14 kernel with vlan support. apart from building
vconfig for the cris, what other steps will i have to take to enable
vlan support on the devboard_lx?
TIA,
akshay